Selecting a Suitable Remote Phosphor Configuration for Improving Color Quality of White Led (original) (raw)
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TELKOMNIKA Telecommunication Computing Electronics and Control, 2019
Remote phosphor structure has higher luminous efficiency comparing to that of both conformal phosphor and in-cup phosphor structures. However, it is hard to control the color quality of remote phosphor structure, and this issue has become one of the most researchable objectives to many researchers in recent years. Up to now, there are two remote phosphor structures applied to improve the color quality, including dual-layer phosphor configuration and triple-layer phosphor configuration. The purpose of this research is to select one of those configurations to have multi-chip white LEDs (WLEDs) achieved the highest color rendering index (CRI), color quality scale (CQS), luminous efficacy (LE), and color uniformity. In this research, WLEDs with two correlated color temperatures (CCT) of 6600K and 7700K were applied. The obtained results showed that triple-layer phosphor configuration is more outstanding in CRI, CQS, and LE. Moreover, the color deviation has been significantly reduced, which means the color uniformity has been enhanced with the application of triple-layer phosphor configuration. These results can be proven by scattering properties of phosphor layers based on Mie theory. Thus, the researched results have become a reliable and valuable reference for manufacturing higher-quality WLEDs.
International Journal of Electrical and Computer Engineering (IJECE), 2020
In this manuscript, we presented a research that enhance the performance of WLED using the multi-phosphor configuration. The phosphor layers in the research are separated from each other to achieved better luminous efficiency, however, it makes controlling color light quality more complex. Another issue is finding out the whether two layers of phosphor or three layers of phosphor is better in improving color quality. The research addressed this issue by analyzing the optical aspects of the respective WLEDs that employ these structure. The studied aspects are quality indicators such as luminous efficacy (LE), and color uniformity, color rendering index (CRI), color quality scale (CQS). The results of the experiments in this research, which come from the employment of WLEDs with 2 color temperatures 5600 K and 8500 K, suggest that WLED with three phosphor layers is better in CRI, CQS, LE. This type of phosphor structure also limits the color deviation significantly, thus, improves the color uniformity. This results is verifies with Mie theory, therefore, can be applied as reference or guideline for production of better WLEDs.
The options in remote phosphor structure for better white LEDs color quality
TELKOMNIKA (Telecommunication Computing Electronics and Control), 2020
The WLEDs configuration with remote phosphor layers has higher luminescent performance than WLEDs with dispense coating or conformal coating and is applied for many modern devices. However, managing the chromatic performance of lighting structure with remote phosphor materials is a challenging objective that demands more research. This has inspired the usage of multi phosphor configurations with distance in between the layers to improve color quality. The results of this manuscript can support the manufacturers in choosing the optimal configuration for optical performance in LEDs devices with more than one phosphor material. The simulated model used in the experments is 6500 K CCT WLEDs, which results show the triple-layers structure is more favorable in terms of color quality and light output. Besides, a notable reduction occurs in color deviation means that chromatic stability is also enhanced in WLEDs with three phosphor layers. Through experimental results, which were confirmed by the Mie-scattering theory, this research offers valuable approach and details to produce better WLEDs.
Influence of Dual-layer and Triple-layer Remote Phosphor Package on Optical Properties of White LEDs
TELKOMNIKA (Telecommunication Computing Electronics and Control), 2018
In this paper, the influence of the distance between phosphor layers in the dual-layer and triplelayer remote package on luminous flux and color rendering property is presented and analyzed. During the simulation, it is recognized that an appropriate distance can produce higher quality of the multi-chip white LED (MCW-LEDs) through adjusting the distance between two and three phosphor layers. According to the research results, 0.1mm is the outstanding distance between two phosphor layers so that the performance of MCW-LEDs can be accomplished the best optimal effect. In addition, the simulation results show that the dual-layer structure yielded higher optical properties than the triple-layer structure in relation to the distance. The highest lumen output of triple layer-structure can be achieved at the distance of 0.6 mm and dual-layer structure is 0.1 mm. Meanwhile, the color rendering index (CRI) changes insignificantly when the distance increases. Triple layer package is not practical for high power white LEDs due to high cost and low conversion efficiency. Dual-layer remote phosphor package with the distance between two phosphor layers of 0.1mm is an optimal structure of LEDs in improving the luminous efficiency and the color quality.
Nucleation and Atmospheric Aerosols, 2021
This research suggests using triple-layer remote phosphor (TRP) to improve the color quality and luminous flux coming out of white LEDs (WLEDs). The TRP structure contains three different phosphor layers: beneath is the yellow phosphor YAG:Ce 3+ , a red phosphor LiInO2:Eu 3+ above, and a green phosphor Zn2GeO4:Mn 2+ in within. Controlling the red-light composition with a red phosphor layer LiInO2:Eu 3+ leads to a higher color rendering index (CRI). Thus, increase the luminous efficacy (LE) of WLEDs using a green phosphor layer of CaLaB3O7:Ce 3+ ,Mn 2+ to monitor green light composition. Additionally, when increasing these two phosphor concentrations, the yellow concentration YAG:Ce 3+ decreases to keep the average correlated color temperatures (ACCTs) within 6000K-8500K. Besides CRI and LE, controlling green and red phosphor concentration is also a way to analyze the color quality scale (CQS). The study result shows that the higher the LiInO2:Eu 3+ concentration, the greater the CRI value. However, CRI significantly reduces when increasing Zn2GeO4:Mn 2+ concentration. Meanwhile, CQS can raise a substantial amount in the concentration range of 10%-14% LiInO2:Eu 3+ , flout LiInO2:Eu 3+ concentration. Peculiarly, parallel with the improvement of CRI and CQS, LE also grows over 40% due to a decrease in backscattering light and added green light. This research may be valuable for manufactures for improving the color quality and luminous flux of WLEDs.
Materials Science-Poland
Angular color distribution uniformity has been one of the most relevant properties in the development of white light-emitting diodes (WLEDs), since color consistency and uniformity are crucial factors in quality evaluation of a WLED. Here, particularly considering the need to overcome the poor chromaticity usually associated with WLED, we introduce a new design for the remote-phosphor package, namely a three-layered or triple-layer (TL) phosphor structure. Using three phosphor layers in packaging a WLED can result in higher color quality and luminous efficacy, compared to the double-layer (DL) configuration. In the present study, the results of using three remote phosphor layers indicate that although the structure using three layers has a lower color rendering index, the color quality scale is better than that available from the package with two layers. Additionally, the color-deviation values in the TL structure are smaller than in the dual-layer one, especially at high color temp...
TELKOMNIKA Telecommunication Computing Electronics and Control, 2020
The remote phosphor structure is disadvantageous in color quality but more convenient in luminous flux when compared to conformal phosphor or in-cup phosphor structure. From this disadvantage, there are many studies to improve the color quality of the remote phosphor structure. This research will propose a dual-layer remote phosphor structure to improve color rendering index (CRI) and color quality scale (CQS) of WLEDs. The WLED package with color temperature of 8500 K is utilized in this study. The idea of the study is to locate a layer of phosphor green Y2O2S:Tb3+ or red ZnS:Sn2+ on the yellow phosphor YAG:Ce3+ film, and then finding the suitable added concentration of ZnS:Sn2+ to match the highest color quality. The results showed that ZnS:Sn2+ brings great benefits to increase CRI and CQS. The greater the ZnS:Sn2+ concentration is, the higher the CRI and CQS become owing to the rise in red light components in WLEDs. Meanwhile, the green Y2O2S:Tb3+ phosphor brings benefits to luminous flux. However, the decrease in luminous flux and color quality occurs when the concentration of ZnS:Sn2+ and Y2O2S:Tb3+ exceeds the corresponding level. This is proved by applying Mie-scattering theory and Lambert-Beer's law. The results of articles are important for WLEDs’ fabrication having higher white light quality.
Patterned structure of REMOTE PHOSPHOR for phosphor-converted white LEDs
Optics Express, 2011
High efficiency white light-emitting diodes with superior colormixing have been investigated. It is suggested that the patterned remote phosphor structure could improve the uniformity of angular-dependent correlated color temperature (CCT) and achieve high chromatic stability in wider operating current range, as compared to the conventional remote phosphor coating structure. In this experiment, we employed a pulse spray coating method to place the patterned phosphor on the package and to leave a window region. The window area, a clear space without coating of the phosphor not only increases the extraction efficiency of blue rays at large angle, but also improves the stability of angular-dependent CCT. Moreover, the CCT deviation could be reduced from 1320 K to 266 K by this patterned remote phosphor method, and the stray blue/yellow light within the package can be effectively reduced and controlled. The design was verified both experimentally and theoretically.
International Journal of Electrical and Computer Engineering (IJECE), 2020
The effects of red light-emitting phosphor CaMgSi2O6:Eu2+,Mn2+ on the optical properties of single-layer remote phosphor structure (SRPS) and dual-layer remote phosphor structure (DRPS) are the focus of this study. The differences in color quality and luminous flux (LF) of white light-emitting diodes (WLEDs) between these two structures are also revealed and demonstrated based on the Mie theory. SRPS consists of one mixed phosphor layer betweenCaMgSi2O6:Eu2+,Mn2+ andYAG:Ce3+particles, while DRPS includes two separated layers: red phosphor layer and yellow phosphor layer. In this work, 5% SiO2 is added into the phosphor layers to increase scattering abilities. Discrepancies in structures greatly affect the optical characteristics of WLEDs. The results showed that the color rendering index (CRI) increased with the concentration in both structures with nearly equal values. Meanwhile, color quality scale (CQS) of DPRS is 74 at ACCTs ranging from 5600K to 8500K, higher than CQS of SRPS w...
TELKOMNIKA, 2022
This article compares the lumen output of two packages of two-remote phosphor (RP). The first package is flat dual-remote phosphor (FDRPS). The second package is concave dual-remote phosphor (CDRP). The dispersion qualities of the white-light-emitting diode are different as a result of their different cover designs, leading to a disparity between the FDRPS and CDRPS configurations. The results of the study show that the FDRPS package yields a lumen output superior to that of the CDRPS package. In the article, we can also see how the space among the phosphor films (1) and the space among the phosphor film and the light emitting diodes (LED) outer side (2) might affect the light characteristics in the CDRPS model. As the indicated distances shift, the characteristics of dispersion and absorptivity in the distant phosphor film will shift as well. Such an occurrence can have an impact on chromatic uniformity as well as optical performance in white light emitting diodes (WLEDs). If we modify the 1 and 2 values, it is necessary to change the phosphor YAG:Ce 3+ concentration in the WLEDs to keep the correlated color temperature at 8500 K.